Siege of Boston

The Siege of Boston (19 April 1775-17 March 1776) was a major action and the opening phase of the American Revolutionary War. Almost 20,000 New England militiamen surrounded the city of Boston, Massachusetts, which was occupied by 11,000 British troops under the generals Thomas Gage, William Howe, and Henry Clinton. The city was evacuated in March 1776 after the colonists fortified Dorchester Heights with artillery.

Following the Battles of Lexington and Concord, militia from surrounding Massachusetts communities blocked land access to Boston. The Continental Congress formed the Continental Army from the militia, with George Washington as its commander-in-chief. In June 1775, the British suffered heavy losses at the Battle of Bunker Hill, during which the British drove the Continentals from their siege positions on Bunker and Breed's Hills. For the rest of the siege, military actions were limited to occasional raids, minor skirmishes, and sniper fire.

In November 1775, Washington sent the 25-year-old former bookseller Henry Knox to Fort Ticonderoga to gather its captured artillery for the Siege of Boston. Knox's "Noble train of artillery", some 60 tons of cannons and other armaments, was brought along poor-quality roads and frozen rivers in the snow. These cannons arrived in January 1776, and Washington had Dorchester Heights fortified in March 1776. William Howe, seeing his positions in Boston as indefensible, reached a gentleman's agreement with Washington; if Washington allowed for Howe to evacuate the garrison of the city and its loyalist inhabitants without being fired upon, Howe would not burn the city. 120 British ships evacuated 10,000 British troops and 1,000 loyalists to Halifax, Nova Scotia, and the loyalists and British soldiers ravaged Boston before leaving. Washington's bluff had won America a strategic victory, with Boston becoming an American stronghold.